OpenSSH now uses hybrid post-quantum streamlined NTRU Prime X25519 by default

Re:OpenSSH now uses hybrid post-quantum streamlined NTRU Pri... by vzaliva on Saturday April 09, 2022 @09:13PM (#30973625)

It mentions only "key exchange method". Does it mean we can keep our old keys or it requires different types of keys to be used?

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Re:OpenSSH now uses hybrid post-quantum streamlined NTRU Pri... by sz3 on Sunday April 10, 2022 @04:50AM (#30975433)

Different keys.

For example, you might currently be using a public/private keypair for 4096-bit RSA. That keypair (by definition) only works for the RSA key exchange algorithm. Likewise, an x22519 keypair is for the x25519 key exchange.

A sntrup761x25519 keypair will be its own thing. As an aside, a sntrup761x25519 public key will be two public keys glued together (one for each algorithm). [1] Likewise for the private key.

(one could reuse an existing x25519 keypair for the x25519 component of sntrup761x25519, but it seems like a bad idea)

[1] https://github.com/openssh/openssh-portable/blob/master/kexs...

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Re:OpenSSH now uses hybrid post-quantum streamlined NTRU Pri... by ttybird2 on Sunday April 10, 2022 @07:15AM (#30976101)

Same keys, servers and clients will keep using their ed25519 keys for authenticating each other, the keys for the key exchange are negotiated on login.

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Re:OpenSSH now uses hybrid post-quantum streamlined NTRU Pri... by sz3 on Sunday April 10, 2022 @02:41PM (#30980286)

Huh! Thanks for the correction.

That makes a lot of sense -- I have some more reading to do...

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